Low power and Lossy Networks (LLNs), e.g., sensor networks, have a myriad of applications, such as Smart Grid and Smart Cities. Various challenges are presented with LLNs, such as lossy links, low bandwidth, battery operation, low memory and/or processing capability of a device, etc. Changing environmental conditions may also affect device communications. For example, physical obstructions (e.g., changes in the foliage density of nearby trees, the opening and closing of doors, etc.), changes in interference (e.g., from other wireless networks or devices), propagation characteristics of the media (e.g., temperature or humidity changes, etc.), and the like, also present unique challenges to LLNs.
The myriad of challenges in LLNs makes supporting device mobility particularly difficult. Generally speaking, device mobility refers to the ability of a device to move from using one parent node in the network to using another node for purposes of routing traffic. In some cases, for example, the device may physically move to another location, necessitating the parent change. In other cases, a parent change may also be necessitated by other factors, such as changing environmental conditions typical in LLNs (e.g., the current parent of a node becomes unreachable due to an obstruction, etc.), without physical movement of the device.
With each potential parent change by nodes in an LLN, the routing topology of the network may require updating. However, sending routing protocol messages to effect such a change may also impinge on the function of the network. In particular, since the devices in an LLN often have constrained resources and use low bandwidth links, transmitting routing updates too frequently may negatively affect network traffic.